1. Field of the Invention
The invention relates in general to a method for strengthening glass and a glass using the same, and more particularly to a method for strengthening glass capable of controlling the cambering of the glass and a glass using the same.
2. Description of the Related Art
Float process is one of the methods for manufacturing glass substrate. During the float process, a glass solution in a molten state is placed on a tin solution, one surface of the glass solution contacts the tin solution, and the other surface of the glass solution is exposed in the air, and the glass solution in a molten state, after cooling down, is solidified as a glass substrate in a solid state. Following the formation process, a strengthening process is applied to the glass substrate. Let the ion-exchange strengthening process be taken for example. The glass substrate is immersed in a potassium nitrate solution. Due to the diffusion reaction between the sodium ions of the glass substrate and the potassium ions of the potassium nitrate solution, the potassium ions enter the glass to replace the sodium ions, so that the lattice structure of the glass substrate changes and the glass is strengthened. The size of the potassium ions is larger than that of the sodium ions.
Referring to FIG. 1 (prior art), a cross-sectional view of a generally known strengthened glass substrate is shown. Since the first surface 16 of the glass substrate 12 contacts the tin solution, the first surface 106 has more tin particles aggregated thereon than the second surface. During the process of strengthening the glass substrate, the first surface 16 uses tin particles as a barrier to limit the potassium ions of the potassium nitrate solution in the quantity entering the first surface 16. Consequently, due to the large difference between the quantity of the potassium ions entering the first surface 16 of the glass substrate 12 and the quantity of the potassium ions entering the second surface 18 of the glass substrate 12, the internal stress of the first surface 16 is thus different from the internal stress of the second surface 18, and the glass substrate 12 is cambered as indicated in FIG. 1.